Banking with a computer is pretty safe as long as you're careful. However, hackers increasingly try to get cash when they see an opportunity.
The best way to protect your account is to make sure you use the Internet safely. If there's any nasty software on your computer, you risk handing over passwords. Sophisticated programs can even set up transfers from your account the instant you log in - and hide those transfers until you view your account from another computer.
It's also best to avoid using unencrypted wireless networks (like many free public services). Google's recent scandal over accidentally collecting wireless data shows how easy it is for data to go end up in surprising places.
The bottom line: be careful with computers and networks you use to bank online, and you improve your chances dramatically. However, check your account transactions regularly just in case.
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